How to merge two in-page configs?

HI,

Version used 3.5.2

I try something like this:

var config = {  toolbar  :  'Basic'  };
var extra = { width :  '600px' };

jQuery.extend( config, extra );

CKEDITOR.replace( 'textareaId', config ) ;

this always fails with "Uncaught TypeError: Cannot read property 'length' of undefined" in ckeditor.js.

I also tried:

var config = {};
for( var prop in config1) { config[prop] = config1[prop]; }
for( var prop in config2) { config[prop] = config2[prop]; }

//or in a for-in loop like 
for(var prop in config2) { config1[prop] = config2[prop]; }

none work. Why? And how do I make it work?

Thanks in advance.

Regards